Do you have inpatient pediatric experience as a RN? In my area one of the children's hospitals does not yet require peds/acute care certification but they look at your nursing background and your NP experience. For example, I have a friend that works at Boston Children's in the Cardiac Intensive Care Unit and her degree was peds primary care and she got the job because she has years of experience in a PICU setting.
The other Children's Hospital near requires peds-acute care certification in certain inpatient areas (PICU, ED, CCU,etc) But is still okay with peds primary care for inpatient medical floors (Nephrology, endocrine, pulmonary, etc). I think it depends what state your in and what type of position. But still not a bad idea to consider a peds acute care post-masters program in the future.